1. Field of the Invention
This invention provides means and methods for fabricating mandrel bars from recycled used segments of mandrel bars used in the manufacture of seamless pipe.
2. Description of Prior Art
In the manufacture of seamless steel pipe, mandrels are used to support the interior of a hollow article being rolled into the form of a pipe. Such mandrels are subjected to extremely harsh mechanical and chemical environmental conditions and, despite their fabrication of wear- and corrosion-resistant steels, such as H-13 chromium steels, they need to be replaced frequently, at great expense. Such wearing of the mandrels is uneven; some parts of the mandrel may be so worn as to be useless for further service, while other segments may be in comparatively good condition. Nevetheless, under such circumstances, it has been the practice to discard the entire mandrel and install a new one.
It is an object of the present invention to recover reusable segments of such mandrels and to join such segments together, by a special welded and threaded joint, to form a useful new mandrel.